2. Field of the Invention
The present invention relates generally to the coloring of hair, and in particular to a composition and method for simultaneously lightening and coloring hair in a single step using one or more basic dyes.
3. Description of the Related Art
Melanin is a pigment which provides hair with its natural color. Melanin can be found in granular form in the cortex of hair follicles. There are two general classes of melanin pigments: eumelanins and pheomelanins. Eumelanins are brownish-black in hue, while pheomelanins are reddish-orange in hue. Darker hair typically has a higher concentration of eumelanins, while reddish hair typically has a higher concentration of pheomelanins. Light blond hair typically has a low concentration of both pigments.
Dark hair color can be lightened by applying a bleaching agent to the hair to attack and destroy the melanin granules. The bleaching agent typically includes a hydrogen peroxide solution. The hydrogen peroxide solution can be used alone, or in combination with anhydrous powders such as silicate and/or carbonate salts or persulfate salts of ammonium, potassium or sodium. The mixture of hydrogen peroxide and anhydrous powder is beneficial if stronger bleaching is desired, such as, for example, when lifting brown or darker hair to a pale blonde color.
During hair bleaching, pheomelanins are typically more difficult to destroy than eumelanins. As a result, dark hair tends to take on a reddish or orange tone when bleached due to the pheomelanin pigment remaining in the hair. In order to neutralize this reddish or orange tone, colorants or dyes are typically applied to the hair either during or after bleaching.
It is known that certain basic dyes can be combined with a bleaching mixture such that when the combination is applied to the hair, the hair is bleached and toning or coloring is imparted to the hair in a single step. For example, U.S. Pat. No. 6,440,177 to Orr teaches that the basic azo dyes listed in Table 1 below have been found to effectively color bleached hair. The listed dyes have been found to be stable in the bleach mixture and capable of depositing the desired amount of tone on the hair.
TABLE 1Functioning One-Step Dyes under U.S. Pat. No. 6,440,177Toning ability/Stability (5 beingDyeChemicalClassC.I. #highest)Basic Blue41Azo111543Basic Blue67Azo451754Basic Brown1Azo210002Basic Brown4Azo210102Basic Red18Azo110855Basic Red22Azo110554Basic Red46Azo5Basic Red104Azo5Basic Violet35Azo4Basic Yellow45Azo2Basic Yellow57Azo2Basic Yellow67Azo2
The Orr patent also teaches that certain other basic azo dyes, for example Basic Blue 54, are not effective as one step colorants, as they are generally unstable in the bleaching mixture and/or ineffective in depositing tone or coloring on the hair.
The dyes listed in Table 1 only represent certain particular shades of the respective colors. As a result, these particular dyes may not produce the desired shade or tone when applied to a person's hair, either alone or in combination with other dyes. This is particularly true when the person's hair has been bleached to a very pale blond shade, such that the tone that results from application of dye is particularly noticeable.
Additionally, even if one or more of the listed dyes in Table 1 provides the desired tone, the dyes may not exhibit the desired colorfastness or purity properties. Further, the dyes may be prohibitively expensive. In addition, it may be necessary to use a selected dye in large amounts or at very high concentrations to achieve the desired tone or colorfastness, which may result in diminished stability of the dye in the bleaching solution.
It would be advantageous to provide a composition and method for hair lightening and coloring in a single step that produces the desired toning and stability characteristics when used in limited amounts and/or at high concentrations in a person's hair. It would also be advantageous to provide a composition and method for hair lightening and coloring that provides the desired shade of color to a person's hair while also being generally stable in a bleach solution and effective in depositing tone on the hair for an extended period of time.
Accordingly, prior to the development of the present invention, there has been no composition and method for hair lightening and coloring in a single step that: provides desired toning and stability characteristics when used in limited amounts and/or at high concentrations; and provides a desired shade of color to hair while being generally stable in a bleach solution and effective in depositing the tone on the hair for an extended period of time. Therefore, the art has sought a composition and method for hair lightening and coloring that exhibits desired toning features and stability, particularly when used in limited amounts and at high concentrations; and provides a desired shade of coloring to hair while being generally stable in the bleach solution and effective in depositing the tone on the hair for an extended period of time.